Central heating and/or cooling systems typically employ a central fluid heating and/or cooling plant and respective conduits for directing the heated or cooled fluid to the rooms, offices, etc. in the house, unit or commercial building being serviced by the system. In forced air systems, a furnace and/or air conditioner is employed to heat or cool air which is forced through air ducts to the various rooms. In forced water systems, a water heater and/or cooler is employed to heat or cool water which is pumped through pipes to heat exchangers located in the various rooms. Steam heating systems are akin to hot water systems except that a boiler is employed to generate steam which is directed by pipes to radiators located in the various rooms.
In such systems, usually a single thermostat located in one of the heated or cooled rooms is employed to control operation of the system. The thermostat may be set to desired room temperature whereupon the system operates automatically to maintain such temperature in the room containing the thermostat. At the same time, the other rooms, offices, etc. being serviced will be heated or cooled, but without provision for automatic individual temperature control.
In houses, other residential units and commercial buidlings employing such systems, the various rooms thereof typically are heated or cooled both day and night. Consequently, rooms (or zones consisting of one or more rooms) are heated or cooled during daily periods of minimal or no use. For example, the bedrooms in a house continue to be heated or cooled during the daytime when most activity occurs in the non-sleeping areas of the house such as the living room, dining room and kitchen, whereas the latter areas continue to be heated or cooled along with the bedrooms at night. In commercial buildings, unused offices or other daytime use rooms may continue to be heated just to maintain a comfortable environment in localized maintenance and/or security areas or rooms. Obviously, the heating or cooling of a room or zone not in use or having minimal use for a substantial portion of the day is of minimal benefit and a waste of energy in a practical sense.
In view of the foregoing, considerable energy savings could be obtained with minimal compromise in comfort by eliminating unnecessary heating or cooling of rooms during cyclical or daily periods of low or no use on a room by room or zone by zone basis. Although individual control of room heating or cooling may to some extent be obtained by going from room to room and opening or closing the air vents in the case of forced air systems or heat exchanger valves in the case of water or steam systems, such practice is tedious, subject to forgetfulness or tardiness, and overall inconvenient. Also, loose or poorly fitting closures for the air vents would reduce potential savings. This practice of course is contingent upon each room or zone having a shut-off device. Moreover, there is no provision for preheating a room or zone prior to use absent advance manual attention thereto.